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United States Patent |
5,664,242
|
Takagi
|
September 2, 1997
|
Automatic exposure device and photometry device in a camera
Abstract
An automatic exposure device in a camera divides an object field into a
plurality of areas and photometers them by the use of a divisional
photometry element, and calculates optimum exposure from the result of the
photometry. The divisional photometry element includes a photometric
converting portion for photoelectrically converting incident light in each
of the areas and putting out an output, and a reading portion for reading
out the plurality of outputs of the photoelectric converting portion. When
the number of successive outputs of a row of the areas in the readout
direction which exceed a predetermined value is greater than a
predetermined number, the output of that row is completely omitted in the
calculation of the optimum exposure.
Inventors:
|
Takagi; Tadao (Yokohama, JP)
|
Assignee:
|
Nikon Corporation (Tokyo, JP)
|
Appl. No.:
|
702856 |
Filed:
|
August 26, 1996 |
Foreign Application Priority Data
Current U.S. Class: |
396/234; 396/268; 396/273 |
Intern'l Class: |
G03B 007/08 |
Field of Search: |
348/243
396/268,273,234
|
References Cited
U.S. Patent Documents
3179808 | Apr., 1965 | Grey et al. | 354/429.
|
3904818 | Sep., 1975 | Kovac | 358/160.
|
4476383 | Oct., 1984 | Fukuhara et al. | 354/432.
|
4567525 | Jan., 1986 | Endo et al. | 358/213.
|
4703442 | Oct., 1987 | Levine | 358/163.
|
4705382 | Nov., 1987 | Mukai et al. | 354/432.
|
4739495 | Apr., 1988 | Levine | 358/163.
|
4870443 | Sep., 1989 | Hayakawa et al. | 354/432.
|
Foreign Patent Documents |
1-288735 | Nov., 1989 | JP.
| |
Primary Examiner: Adams; Russell E.
Parent Case Text
This application is a continuation, of application Ser. No. 08/274,370,
filed Jul. 13, 1994, now abandoned, which is a continuation of application
Ser. No. 08/091,821, filed Jul. 13, 1993, now abandoned.
Claims
What is claimed is:
1. In an automatic exposure device in a camera in which an object field is
divided into a plurality of areas forming a plurality of rows and
photometered by the use of a divisional photometry element and optimum
exposure is calculated from a result of the photometry, the improvement
wherein said divisional photometry element includes a photoelectric
converting portion for photoelectrically converting incident light in each
row of said areas and putting out a plurality of outputs, and a reading
portion for reading out the plurality of outputs of said photoelectric
converting portion, and wherein when a number of successive outputs of a
row of said areas in a readout direction which exceed a predetermined
value is greater than a predetermined number, the outputs of that row are
completely omitted in calculation of the optimum exposure.
2. The device of claim 1, wherein said photoelectric converting portion is
of a charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
3. The device of claim 1, wherein when the number of rows with omitted
outputs exceeds a predetermined number, said divisional photometry element
is not used for calculation of the optimum exposure.
4. The device of claim 3, wherein when he number of rows with omitted
outputs exceeds a predetermined number, said calculation of the optimum
exposure is effected by use of an output of a photometry element discrete
from said divisional photometry element.
5. The device of claim 4, wherein said discrete photometry element is a
photodiode.
6. An automatic exposure device in a camera comprising:
divisional photometry means for photometering an object field in each of a
plurality of divisional areas, said photometry means including
photoelectric conversion means for photoelectrically converting incident
light in each of a plurality of areas forming a plurality of rows dividing
the object field and putting out a plurality of photoelectric outputs, and
reading means for successively reading out the plurality of photoelectric
output in each row of said areas; and
calculation means for calculating an optimum exposure value on the read-out
photoelectric outputs;
wherein when a number of successive outputs of a row of said areas in a
readout direction which exceed a predetermined value is greater than a
predetermined number, said calculation means completely omits the outputs
of that row in calculation of the optimum exposure value.
7. The device of claim 6, wherein said photoelectric conversion means is of
a charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
8. The device of claim 6, wherein when the number of rows with omitted
outputs exceeds a predetermined number, said divisional photometry means
is not used for calculation of the optimum exposure value.
9. The device of claim 8, wherein when the number of rows with omitted
outputs exceeds a predetermined number, said calculation of the optimum
exposure value is effected by use of an output of photometry means
discrete from said divisional photometry means.
10. The device of claim 9, wherein said discrete photometry means is a
photodiode.
11. In an automatic exposure device in a camera in which an object field is
divided into a plurality of areas and photometered by the use of a
divisional photometry element and optimum exposure is calculated from a
result of the photometry, the improvement wherein said divisional
photometry element includes a first photoelectric converting portion for
photoelectrically converting incident light in each of said areas and
putting out an output, a second photoelectric converting portion, having a
surface shielded from light, for measuring a dark signal and putting out
an output, and a reading portion for reading out the outputs of said first
and second photoelectric converting portions in common, and wherein when
the output from said second photoelectric converting portion exceeds a
predetermined value, said divisional photometry element is not used for
calculation of the optimum exposure.
12. The device of claim 11, wherein said photoelectric converting portions
are of a charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
13. The device of claim 11, wherein when the output from said second
photoelectric converting portion exceeds said predetermined value, said
calculation of the optimum exposure uses an output of a photometry element
discrete from said divisional photometry element.
14. The device of claim 13, wherein said discrete photometry element is a
photodiode.
15. The device of claim 11, wherein when the output from said second
photoelectric converting portion exceeds said predetermined value, a
preset value is used as the optimum exposure value.
16. An automatic exposure device in a camera comprising:
divisional photometry means for photometering an object field in each of a
plurality of divisional areas, said divisional photometry means including
photoelectric conversion means for photoelectrically converting incident
light in each of a plurality of areas provided by dividing the object
field and putting out an output, second photoelectric conversion means
having a surface shielded from light, for measuring a dark signal and
putting out an output, and reading means for reading out the outputs of
said first and second photoelectric conversion means in common; and
calculation means for calculating an optimum exposure value based on the
read-out photoelectric outputs;
wherein when the output from said second photoelectric conversion means
exceeds a predetermined value, said divisional photometry means is not
used for calculation of the optimum exposure.
17. The device of claim 16, wherein said photoelectric conversion means are
of a charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
18. The device of claim 16, wherein when the output from said second
photoelectric conversion means exceeds said predetermined value, said
calculation of the optimum exposure value uses an output of photometry
means discrete from said divisional photometry means.
19. The device of claim 18, wherein said discrete photometry means is a
photodiode.
20. The device of claim 16, wherein when the output from said second
photoelectric conversion means exceeds said predetermined value, a preset
value is used as the optimum exposure value.
21. A photometry device in a camera comprising:
a plurality of first photoelectric converting portions for photometering an
object field and putting out outputs;
a second photoelectric converting portion, having a surface shielded from
light, for measuring a dark signal and putting out an output; and
reading means for reading out the outputs of said first and second
photoelectric converting portions in common;
wherein when the outputs of said photoelectric converting portions exceed a
predetermined output, it is judged that the outputs of said plurality of
first photoelectric converting portions are unreliable.
22. An automatic exposure device in a camera comprising:
a divisional photometry device for photometering an object field in each of
a plurality of divisional areas, said photometry device including a
photoelectric converter for photoelectrically converting incident light in
each of a plurality of areas forming a plurality of rows of photoelectric
converting elements dividing the object field and putting out a plurality
of photoelectric outputs, and a reading device for successively reading
out the plurality of photoelectric outputs in each row of said areas; and
a calculator for calculating an optimum exposure value based on the
read-out photoelectric outputs;
wherein when a number of successive outputs of a row of said areas in a
readout direction which exceed a predetermined value is greater than a
predetermined number, said calculator completely omits the outputs of that
row in calculation of the optimum exposure value.
23. The device of claim 22, wherein said photoelectric converter is of a
charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
24. The device of claim 22, wherein when a number of rows with omitted
outputs exceeds a predetermined number, said divisional photometry element
is not used for calculation of the optimum exposure value.
25. The device of claim 24, wherein when the number of rows with omitted
outputs exceeds said predetermined number, said calculation of the optimum
exposure value is effected by use of an output of a photometry device
discrete from said divisional photometry device.
26. The device of claim 25, wherein said discrete photometry device is a
photodiode.
27. An automatic exposure device in a camera comprising:
a divisional photometry device for photometering an object field in each of
a plurality of divisional areas, said divisional photometry device
including a first photoelectric converter for photoelectrically converting
incident light in each of a plurality of areas provided by dividing the
object field and putting out an output, a second photoelectric converter
having a surface shielded from light, for measuring a dark signal and
putting out an output, and a reading device for reading out the outputs of
said first and second photoelectric converters in common; and
a calculator for calculating an optimum exposure value based on the
read-out photoelectric outputs;
wherein when the output from said second photoelectric converter exceeds a
predetermined value, said divisional photometry device is not used for
calculation of the optimum exposure value.
28. The device of claim 27, wherein said photoelectric converters are of a
charge accumulation type in which charges are accumulated for a
predetermined time, and thereafter are read out.
29. The device of claim 27, wherein when the output from said second
photoelectric converter exceeds said predetermined value, said calculation
of the optimum exposure value uses an output of a photometry device
discrete from said divisional photometry device.
30. The device of claim 29, wherein said discrete photometry device is a
photodiode.
31. The device of claim 27, wherein when the output from said second
photoelectric converter exceeds said predetermined value, a preset value
is used as the optimum exposure value.
32. A photometry device in a camera comprising:
a plurality of first photoelectric converting portions for photometering an
object field and putting out outputs;
a second photoelectric converting portion having a surface shielded from
light, for measuring a dark signal and putting out an output; and
a reading device for reading out the outputs of said first and second
photoelectric converting portions in common;
wherein when the outputs of said photoelectric converting portions exceed a
predetermined output, it is judged that the outputs of said plurality of
first photoelectric converting portions are unreliable.
33. A method for automatic exposure in a camera under the control of a
processor, comprising:
dividing an object field into a plurality of areas arranged in rows;
photometering the object field in each of the areas and producing outputs;
comparing the outputs produced in said photometering step with a
predetermined value;
determining whether the number of successive outputs for a row which exceed
the predetermined value, exceeds a predetermined number;
calculating an optimum exposure value on the basis of the outputs produced
in said photometering step; and
omitting from said calculating step, the outputs of any of the rows for
which the number of successive outputs for the row which exceed the
predetermined value, is greater than the predetermined number, thereby
indicating that the row is affected by an overflow due to incident
luminance.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an automatic exposure device and a photometry
device in a camera wherein an object field is divided and photometered.
2. Related Background Art
As a device of this kind, there has heretofore been a device as disclosed,
for example, in Japanese Laid-Open Patent Application No. 1-288735. This
device is such that a plurality of photoelectric conversion elements are
disposed in a package and the object field is divide and photometered by
them to thereby obtain optimum exposure.
However, the prior-art device as described above is of a type in which the
outputs of the photoelectric conversion elements are read out as electric
currents and therefore, is of such structure that wiring is led from each
photoelectric conversion element to an amplifier, and for the convenience
of wiring, the number of divisions could only be less than one hundred.
In contrast with such a limitation, there is conceived a method of using a
CCD image sensor or an MOS image sensor in which the outputs of
photoelectric conversion elements are accumulated as charges for a
predetermined time and the accumulated charges are successively read out.
However, in the sensor of the type as described above in which the
accumulated charges are read out, the photoelectric conversion elements
are connected together through a reading portion, and this has led to a
problem that when very high luminance is incident on some of the
photoelectric conversion elements to cause an overflow, it affects the
outputs of that row or the area around it. If the affected outputs are
intactly used for exposure calculation, exposure will greatly deviate from
the optimum value.
SUMMARY OF THE INVENTION
So, it is the object of the present invention to provide an automatic
exposure device in a camera wherein even when very high luminance is
incident on some photoelectric conversion elements to cause an overflow
and it affects the outputs of that row or the area around it, optimum or
nearly optimum exposure is obtained.
To achieve the above object, in a first aspect of the present invention, a
photoelectric conversion portion and a reading portion for reading out the
output of the photoelectric conversion portion are arranged in a
lattice-like form on a divisional photometry element so that when a
predetermined number of or more outputs of a predetermined value or
greater exist adjacent to one another in any one row in the readout
direction, all of the outputs of that row may not be used for the
calculation of the optimum exposure value.
In a second aspect of the present invention, a first photoelectric
conversion portion for photometering the brightness of the object field, a
second photoelectric conversion portion having its surface shielded from
light and measuring a dark signal, and a reading portion for reading out
the outputs of the first and second photoelectric conversion portions are
arranged in a lattice-like form on a divisional photometry element so that
when the output from the second photoelectric conversion portion is equal
to or greater than a predetermined value, the output of the divisional
photometry element may not be used for the calculation of the optimum
exposure value.
In the present invention, when very high luminance is incident on some
photoelectric conversion elements to cause an overflow and it affects the
outputs of that row or the area around it, the affected outputs can be
omitted in the calculation of exposure and therefore, even in such a case,
it becomes possible to obtain optimum or nearly optimum exposure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a camera having an automatic exposure
device according to the present invention.
FIG. 2 shows a first embodiment of the arrangement of photometry elements
11 and 19.
FIG. 3 shows a second embodiment of the arrangement of photometry elements
11 and 19.
FIG. 4 shows a division pattern when the luminance in the image field is
photometered.
FIG. 5 shows the arrangement of color filters placed on the photoelectric
conversion elements of the photometry element 11.
FIG. 6 shows the structure of the photometry element 11.
FIG. 7 is a block diagram of the present invention.
FIG. 8 is a graph showing the spectral sensitivity characteristics of the
three colors of FIG. 5.
FIG. 9 shows xy chromaticity.
FIG. 10 shows blackbody locus and isochromatic temperature lines.
FIG. 11 is a diagram representing the main algorithm of the CPU 23 of FIG.
7.
FIG. 12 is a detailed diagram of a first algorithm.
FIG. 13 is a detailed diagram of a second algorithm.
FIG. 14 is a detailed diagram of a third algorithm.
FIG. 15 is a detailed diagram of another example of the third algorithm.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a cross-sectional view of a camera having an automatic exposure
device according to the present invention. During finder observation, a
light beam from the object field passes through a taking lens 3 and stop 4
in a taking lens barrel 2, is reflected by a main mirror 5 (in its
dotted-line state) in a camera body 1, and passes through a screen 6, a
pentagonal prism 7 and an eyepiece 8 to the photographer's eye. A part of
the light beam passes through the pentagonal prism 7 and through a prism 9
and a condensing lens 10 to a photometry element 11. The photometry
element 11 is a colored two-dimensional CCD used in a video camera or the
like and has a structure that can divide the object field into 69
divisions (widthwise).times.15 divisions (lengthwise), totalling 1035
divisions, as shown in FIG. 4, can photometer luminance, and can measure
colors by the repetitive arrangement of filters of three colors, R, G and
B as shown in FIG. 5.
Another part of the light beam passes through the pentagonal prism 7 and
through a condensing lens 18 to a photometry element 19. The photometry
element 19 is an SPD conventionally used for photometry in a camera, and
the output thereof is read as an electric current. The purpose of this
photometry element 19 is to change over the photometry element from 11 to
19 when very high luminance is incident on some of the photoelectric
conversion elements of the photometry element 11 to cause an overflow that
affects the outputs of many areas. The photometry element 19 in the
present embodiment divides the object field into five areas and
photometers them, but may also be an element of the single photometry
type.
ROM 12 in the lens communicates photographing distance information X
obtained from the position of the taking lens 3 and lens data such as the
aperture value information of the stop 4 to the camera body 1.
Posture detecting means 13 detects the posture of the camera body 1.
A photometry element 17 is a flash photometering element used for flash
control when flash means is used. A light beam emitted from the flash
device is reflected by the object field and passes through the taking lens
3, the stop 4 and a shutter 14, and is reflected by a film surface 15 and
passes through a condensing lens 16 to the flash photometering photometry
element 17.
FIG. 2 shows a first embodiment of the arrangement of the photometry
elements 11 and 19. This figure is a view of the pentagonal prism 7 as it
is seen from the eyepiece 8 side, and primarily intends to illustrate the
arrangement, and therefore, the directions, etc. of the elements are
depicted somewhat differently from those in FIG. 1. The photometry element
11 photometers by the use of the light beam above the eyepiece 8, while
the photometry element 19 photometers by the use of the light beams at the
right and left side of the eyepiece. Photometry is effected with the
photometry element divided into the central portion and four areas around
it, totalling five areas, and with regard to the central portion, a pair
of right and left elements are superposed one upon the other on the
photometering area, whereby the outputs are combined to provide the output
of the central portion.
FIG. 3 shows a second embodiment of the arrangement of the photometry
elements 11 and 19. This figure is a view of the pentagonal prism 7 as it
is seen from the eyepiece 8 side, and primarily intends to illustrate the
arrangement, and therefore, the directions, etc. of the elements are
depicted somewhat differently from those in FIG. 1. The photometry element
11 photometers by the use of the light beam above the eyepiece 8, while
the photometry element 19 photometers by the use of the light beam at the
left side of the eyepiece. Photometry is effected in a single area without
the photometry element being divided into a plurality of areas.
FIG. 4 shows a division pattern when the luminance in the image field is
photometered. The photometry element 11 divides the luminance of the
object field image on the screen 6 through the condensing lens 10, as
shown, and photometers it. The division pattern is 1035 divisions, i.e.,
69 divisions (widthwise).times.15 divisions (lengthwise). As regards the
addresses of the respective areas, with the camera body 1 levelled in its
lateral position, the left side of the downside is (1, 1) and the right
side of the upside is (69, 15).
FIG. 5 shows the arrangement of color filters placed on the photoelectric
conversion elements of the photometry element 11.
On the 1035 divided areas illustrated in FIG. 4, there are repetitively
arranged filters of three colors, R, G and B as shown in FIG. 5, whereby
the light can be resolved into three primary colors and photometered. The
three colors of the filters need not always be three primary colors, R, G
and B, but may also be complementary colors.
FIG. 6 shows the structure of the photometry element 11.
Photoelectric conversion elements (photodiodes) 11a are arranged in 69 rows
and in 15 columns. Shift registers (called H registers) 11b are under each
row, and charges created by the photoelectric conversion by the
photoelectric conversion elements 11a are accumulated in an accumulation
portion, not shown, for a predetermined time, thereafter they are
transferred to the H registers at the same time. The H registers transfer
the charges successively in the leftward direction in accordance with a
clock pulse. There is a V register 11c at the left ends of the H
registers, and this V register 11c upwardly transfers the charges
transferred from each H register 11b, converts them into a voltage by
floating diffusion, not shown and thereafter outputs it to an amplifier.
Optical black portions (OPB) 11d are the surfaces of the photoelectric
conversion elements 11a which are shielded from light, and dark signals
are output therefrom. This structure is identical to what has been
described above, except for the portions shielded from light, and the
reading method is also similar to what has been described above. By the
amount of the dark signals being subtracted from the outputs of the
photoelectric conversion elements 11a, the correction of the amount
corresponding to the dark signals is effected.
When a light beam of high luminance exceeding a predetermined quantity is
incident on some of the photoelectric conversion elements 11a, an overflow
is caused and affects the outputs of the other elements in the rows
including the elements on which the light beam of high luminance is
incident, through the H registers. Further, if the amount of the overflow
is great, it may affect even the other H registers through the V register.
FIG. 7 is a block diagram of the present invention.
The output LV(m, n) of the photometry element 11, on the one hand, is
converted into a luminance value BV(m, n) by conventional luminance
information conversion means 21 and input to a CPU 23, and on the other
hand, is converted into a color temperature CT by conventional color
temperature conversion means 22 and input to the CPU 23. The substance of
the conventional color temperature conversion means 22 will be described
later with reference to FIGS. 8-10.
The output CV(n) of the photometry element 19 is converted into a luminance
value DV(n) by conventional luminance information conversion means 27 and
input to the CPU 23.
Position detection means 13 detects the position of the camera body 1 and
inputs the result of the detection to the CPU 23. Specifically, the result
of the position detection is classified into three positions, i.e., a
lateral position, a vertical position in which the pentagonal prism 7 lies
at the right side, and a vertical position in which the pentagonal prism 7
lies at the left side.
Object distance information X obtained from the position of the taking lens
3 and lens data such as the aperture value information of the stop 4 are
input from the taking lens barrel 2 to the CPU 23 in the camera body 1.
The CPU 23 calculates an optimum exposure value BVans on the basis of the
above-mentioned information input thereto, and displays it on display
means 26 through display control means 25. The calculation of the optimum
exposure value BVans will be described later with reference to FIGS. 11
and so on.
Thereafter, a release button, not shown, is depressed, whereby exposure
control means 24 drives the shutter 14 and stop 4 and controls them to the
calculated exposure value BVans.
FIGS. 8 to 10 illustrate the principle of the color temperature conversion
means 22 of FIG. 7.
FIG. 8 shows the spectral sensitivity characteristics of the three colors
of FIG. 5. In FIG. 8, the axis of abscissa represents wavelength and the
axis of ordinate represents sensitivity. The sensitivity of red is
represented by R(.lambda.), the sensitivity of green is represented by
G(.lambda.) and the sensitivity of blue is represented by B(.lambda.).
When the outputs from light receiving portions having the sensitivities
R(.lambda.), G(.lambda.) and B(.lambda.) are defined as X, Y and Z,
respectively, chromaticity coordinates xy are found from the following
equations:
x=X/(X+Y+Z)
y=Y/(X+Y+Z)
FIG. 9 is an xy chromaticity diagram. All colors lie inside or on the line
of the horseshoe shape, and the color of that area is found from the value
of xy found from the above-mentioned equations.
FIG. 10 represents blackbody locus and isochromatic temperature lines.
On which isochromatic temperature line the color rides is examined from the
value of xy found from the above-mentioned equations, whereby the color
temperature is found.
In the present embodiment, 345 color temperatures corresponding to one
third of 1035 areas, i.e., 345 areas, are found, and the color temperature
conversion means 22 finds the color temperature of the whole by the
addition average of them.
FIG. 11 represents the main algorithm of the CPU 23 of FIG. 7.
At a step S1, the luminance values BV(m, n) photometered by the photometry
element 11 and converted by the luminance information conversion means 21
are read.
At a step S2, the dark signal measured by the optical black portions 11d is
subtracted from the luminance values BV(m, n) and OPB correction is
effected.
At a step S3, the number of elements in the row of optical black portions
11d (the row of OPB) whose outputs exceed a predetermined value is counted
and defined as Nopb. The predetermined value is set to a value about twice
as great as the expected maximum value of the dark signal. In a usual
state, the outputs from the optical black portions 11d are of a small
value of the dark signal level. However, when intense light is incident on
any one photoelectric conversion element 11a and the illuminance of the
element surface exceeds a limit value, a great quantity of charges created
therein overflows and passes through the H registers in that row to the V
register and flows into the H registers in the other rows and destroys the
other data. At this time, the charges also flow into the H registers in
the row of OPB and therefore, the outputs thereof assume a great value for
exceeding the level of the dark signal, and it can be discriminated that
there is the possibility of all data having been destroyed (affected).
At a step S4, the number of lateral rows (the direction of H registers) in
which the outputs of seven or more elements exceed a predetermined value
is counted and defined as Novr. The predetermined value refers to a value
lower by about 1 EV than the upper limit value of photometry determined by
the controllable shortest accumulation time and sensitivity, and is of the
order of 10000 lux in terms of element surface illuminance. The level at
which the overflow occurs is higher than this upper limit value of
photometry, and is a value about 100 to 1000 times as high as that and
therefore, cannot be measured as a matter of course. Also, seven
corresponds to a little less than 4 mm in terms of the image field of a 35
mm single-lens reflex camera, and corresponds to a case where the sun is
photographed by a telephoto lens having a focal length of the order of 400
mm. Accordingly, it can be discriminated that when the outputs of seven or
more elements exceed the upper limit value of photometry, there is the
possibility of an overflow having occurred and the data of that lateral
row (the direction of H registers) having been destroyed.
Subsequently, when at a step S5, Nopb=0 and at a step S6, Novr=0, some of
the elements overflow, whereby it is judged that there is no possibility
of the outputs of the other elements which are not overflowing having been
affected, and advance is made to a step S7, where the calculation of the
optimum exposure value is effected by a first algorithm. The first
algorithm calculates with all the outputs of the photometry element 11 as
being effective, and the details thereof will be described later with
reference to FIG. 12.
When at the step S5, Nopb=0, but at the step S6, Novr.noteq.0, advance is
made to a step S8, where whether Novr is 7 or less is discriminated. If
Novr is 7 or less, that is, if Novr is half of the total 15 rows or less,
advance is made to a step S9, where the calculation of the optimum
exposure value is effected by a second algorithm. The second algorithm
calculates while omitting the data of the lateral rows in the photometry
element 11 which have been affected by the overflow, and the details
thereof will be described later with reference to FIG. 13.
Also, when at the step S5, Nopb.noteq.0 or when at the step S8, Novr
exceeds 7, advance is made to a step S10, where the luminance value DV(n)
of the photometry element 19 is read. Advance is then made to a step S11,
where the calculation of the optimum exposure value is effected by a third
algorithm. The third algorithm judges that the data of the photometry
element 11 are all untrustable, and changes them over to the data of the
photometry element 19 and calculates the latter data, or substitutes a
predetermined value for the data of the photometry element 11, and the
details thereof will be described later with reference to FIG. 14. The
photometry element 19 is an SPD conventionally used in the photometry of a
camera, and the outputs thereof are read from respective independent
routes and therefore, by the overflow from some of the elements thereof,
the outputs of the other elements are not destroyed, as are the CCDs used
in the photometry element 11.
FIG. 12 shows the details of the first algorithm.
At a step S21, a maximum luminance value Bmax is extracted from among 1035
luminance value data divisionally photometered by the photometry element
11.
At a step S22, a maximum luminance difference value .DELTA.BV is extracted
from among 1035 luminance value data divisionally photometered by the
photometry element 11.
At a step S23, scene classification is effected in accordance with the
scene classification of Table 1 in which the maximum luminance value
Bmax,and the maximum luminance difference value .DELTA.BV are used in
parameters. For example, when the maximum luminance value Bmax is 6 and
the maximum luminance difference value .DELTA.BV is 3, the scene is
classified as scene "SC-5".
At a step S24, on the basis of the classified scene, six weight
coefficients W1-W6 are read from Table 2. For example, when the scene is
classified as SC-5, W51 is given to W1, W52 is given to W2, W53 is given
to W3, W54 is given to W4, W55 is given to W5, and W56 is given to W6.
At a step S25, the optimum exposure value is calculated from the following
equation:
BVans=W1.multidot.Bmax+W2.multidot.Bmin+W3.multidot.Bmen+W4.multidot.Bup
+W5.multidot.Bdwn+W6,
where
Bmax: the maximum value among 1035 luminance value data divisionally
photometered by the photometry element 11;
Bmin: the minimum value among 1035 luminance value data divisionally
photometered by the photometry element 11;
Bmen: the arithmetical mean value of 1035 luminance value data divisionally
photometered by the photometry element 11;
Bup: the arithmetical mean value of the data of 8 rows at the upside of the
photometry element 11;
Bdwn: the arithmetical mean value of the data of 8 rows at the downside of
the photometry element 11.
The discrimination between the upside and the downside is effected by the
position detecting means 13.
FIG. 13 shows the details of the second algorithm.
At a step S31, the data of such rows in the photometry element 11 in which
the outputs of seven or more elements exceed a predetermined value are
omitted. The predetermined value refers to the predetermined value
described in connection with the step S4 of FIG. 11.
At a step S32, the maximum luminance value Bmax is extracted from among the
luminance value data which have been divisionally photometered by the
photometry element 11 and have not been omitted at the step S31.
At a step S33, the maximum luminance difference .DELTA.BV is extracted from
among the luminance value data which have been divisionally photometered
by the photometry element 11 and have not been omitted at the step S35.
At a step S34, scene classification is effected in accordance with the
scene classification of Table 1 in which the maximum luminance value Bmax
and the maximum luminance difference value .DELTA.BV are used as
parameters. For example, when the maximum luminance value Bmax is 6 and
the maximum luminance difference value .DELTA.BV is 3, the scene is
classified as scene "SC-5".
At a step S35, on the basis of the classified scene, six weight
coefficients W1-W6 are read from Table 2. For example, when the scene is
classified as SC-5, W51 is given to W1, W52 is given to W2, W53 is given
to W3, W54 is given to W4, W55 is given to W5, and W56 is given to W6.
TABLE 1
______________________________________
Bmax
.DELTA.BV Bmax < 5 5 .ltoreq. Bmax < B
8 .ltoreq. Bmax
______________________________________
.DELTA.BV .ltoreq. 2
SC-1 SC-2 SC-3
2 < .DELTA.BV .ltoreq. 4
SC-4 SC-5 SC-6
4 < .DELTA.BV
SC-7 SC-8 SC-9
______________________________________
TABLE 2
______________________________________
Weight coefficients
Scene classification
W1 W2 W3 W4 W5 W6
______________________________________
SC-1 W11 W12 W13 W14 W15 W16
SC-2 W21 W22 W23 W24 W25 W26
SC-3 W31 W32 W33 W34 W35 W36
SC-4 W41 W42 W43 W44 W45 W46
SC-5 W51 W52 W53 W54 W55 W56
SC-6 W61 W62 W63 W64 W65 W66
SC-7 W71 W72 W73 W74 W75 W76
SC-8 W81 W82 W83 W84 W85 W86
SC-9 W91 W92 W93 W94 W95 W96
______________________________________
At a step S36, the optimum exposure value is calculated from the following
equation:
BVans=W1.multidot.Bmax+W2.multidot.Bmin+W3.multidot.Bmen+W4.multidot.Bup
+W5.multidot.Bdwn+W6,
where
Bmax: the maximum value among the luminance value data which have been
divisionally photometered by the photometry element 11 and have not been
omitted at the step S31;
Bmin: the minimum value among the luminance value data which have been
divisionally photometered by the photometry element 11 and have not been
omitted at the step S31;
Bmen: the arithmetical mean value of the luminance value data which have
been divisionally photometered by the photometry element 11 and have not
been omitted at the step S31;
Bup: the arithmetical mean value of the luminance value data among the data
of 8 rows at the upside of the photometry element 11 which have not been
omitted at the step S31;
Bdwn: the arithmetical mean value of the luminance value data among the
data of 8 rows at the downside of the photometry element 11 which have not
been omitted at the step S31.
The discrimination between the upside and the downside is effected by the
position detecting means 13.
FIG. 14 shows a first embodiment of the details of the third algorithm.
At a step S41, the maximum luminance value Bmax is extracted from among
five luminance value data divisionally photometered by the photometry
element 19.
At a step S42, the maximum luminance difference value .DELTA.BV is
extracted from among five luminance value data divisionally photometered
by the photometry element 19.
At a step S43, scene classification is effected in accordance with the
scene classification of Table 1 in which the maximum luminance value Bmax
and the maximum luminance difference value .DELTA.BV are used as
parameters. For example, when the maximum luminance value Bmax is 6 and
the maximum luminance difference value .DELTA.BV is 3, the scene is
classified as scene "SC-5".
At a step S44, on the basis of the classified scene, weight coefficients
G1-G6 are read from Table 3. For example, when the scene is classified as
SC-5, G51 is given to G1, G52 is given to G2, G53 is given to G3, G54 is
given to G4, G55 is given to G5, and G56 is given to G6.
TABLE 3
______________________________________
Weight coefficients
Scene classification
G1 G2 G3 G4 G5 G6
______________________________________
SC-1 G11 G12 G13 G14 G15 G16
SC-2 G21 G22 G23 G24 G25 G26
SC-3 G31 G32 G33 G34 G35 G36
SC-4 G41 G42 G43 G44 G45 G46
SC-5 G51 G52 G53 G54 G55 G56
SC-6 G61 G62 G63 G64 G65 G66
SC-7 G71 G72 G73 G74 G75 G76
SC-8 G81 G82 G83 G84 G85 G86
SC-9 G91 G92 G93 G94 G95 G96
______________________________________
At a step S45, the optimum exposure value is calculated from the following
equation:
BVans=G1.multidot.Bmax+G2.multidot.Bmin+G3Bmen+G4.multidot.Bup
+G5.multidot.Bdwn+G6,
where
Bmax: the maximum value among five luminance value data divisionally
photometered by the photometry element 19;
Bmin: the minimum value among five luminance value data divisionally
photometered by the photometry element 19;
Bmen: the arithmetical mean value of five luminance value data divisionally
photometered by the photometry element 19;
Bup: the arithmetical mean value of two data at the upside of the
photometry element 19;
Bdwn: the arithmetical mean value of two data at the downside of the
photometry element 19.
The discrimination between the upside and the downside is effected by the
position detecting means 13.
FIG. 15 shows a second embodiment of the details of the third algorithm.
At a step S51, a preset predetermined value 11.3 BV is substituted as the
optimum exposure value.
This method suffers from a disadvantage that accuracy is reduced as
compared with the first embodiment, while on the other hand, it has an
advantage that the photometry element 19 is unnecessary and therefore a
reduction in cost can be achieved.
As described above, according to the present invention, in a photometry
element of the type in which the outputs of photoelectric conversion
portions such as CCDs are used in common and read, when very high
luminance is incident on some of photoelectric conversion elements to
cause an overflow and affects the outputs of that row or the areas around
it, it is accurately detected and the affected outputs can be omitted in
the calculation of exposure and therefore, even in such a case, it becomes
possible to obtain optimum or nearly optimum exposure.
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